Fig. 419.—Aldrovandia vesiculosa: A a plant (nat. size). B Leaf (mag.); the blade is closed; the winged stalk is prolonged into 4–6 irritable bristles.
Fig. 420.—Nepenthes (reduced).
Nepenthaceæ has only 1 genus, Nepenthes (the Pitcher-plant; about 35 species), especially found in tropical E. Asia; the majority are climbing shrubs. The leaf-stalks are twining organs, and terminate either simply in a tendril, or in addition to this, with a pitcher-shaped body (which in some species may be as much as a foot in length) on whose upper edge a lid-like structure is found (Fig. [420]). In this pitcher, as among the Sarraceniaceæ, a fluid is secreted which is able to digest the animals captured (sometimes rather large) and which corresponds in some degree to the gastric juice.
Order 5. Violaceæ (Violets). The flowers are ☿, and generally zygomorphic, hypogynous, with S5, P5, A5, G3 (Fig. [421]). The stamens are closely applied to the ovary, they have a very short filament, and at their summit generally a membranous appendage formed by the prolongation of the connective (Fig. [422] g). The ovary is unilocular with 3 parietal placentæ; style undivided (Fig. [422] B). The fruit is usually a 3-valved capsule, opening along the dorsal sutures (Fig. [423]). Embryo straight; endosperm fleshy (Fig. [425]).—Many are herbaceous plants (e.g. Viola), but in the Tropics shrubs are also found (e.g. Ionidium); a few are lianes; the leaves are scattered, with stipules, and involute in the bud.
Fig. 421.—Diagram of Viola.
Fig. 422.—The large-flowered form of Viola tricolor: A the flower in median longitudinal section; B the gynœceum.